Chip parameters and split types

The chip parameters live in the right-hand panel of CAD Preview. Change one and the solid rebuilds.

Dimensions

Parameter	Default	What it is
Width	40 mm	Chip X extent.
Length	60 mm	Chip Y extent.
Base thickness	4 mm	Total block height.

The channel network’s coordinates are absolute chip millimetres with the origin at the bottom-left, so shrinking the chip does not scale the channels — it moves the walls in around them. Watch the boundary warnings when you do it.

Nothing you have drawn moves when a dimension changes, which is what you want when a feature is placed against a particular edge. When it is not, a resize that leaves the design lopsided offers a Center action, and the Draw tab’s inspector carries the same button under Position. See Centering the design.

Wall rules

Two settings that are easy to confuse.

Wall thickness (default 2 mm) is the minimum material between a channel and anything else, including another channel. It feeds the channels-too-close check, which uses the larger of this and the minimum-printable-wall setting.

Minimum edge spacing (default 3 mm) is specifically about the chip boundary — how close anything may sit to the outside edge. It feeds channel-near-boundary, and it is drawn on the canvas as a dashed rectangle inside the chip outline.

Edge spacing is your design rule, not a printer limit. If your parts release cleanly from a thinner rim, lower it.

Channel defaults

Parameter	Default
Default channel width	0.8 mm
Default channel height	0.5 mm
Default cross-section	rect

These apply anywhere a segment has no dimension marker.

0.8 × 0.5 mm is chosen to sit comfortably above every printer preset’s minimum feature size, so a freshly drawn channel does not start life with a printability warning on it.

Split type

The single most consequential choice on this panel.

Two-piece (the default)

The chip is cut at a plane into a channel plate and a lid. You print both, then bond them.

• The channels are open grooves until the lid goes on, so uncured resin rinses straight out.
• Rectangular channels sit just below the cut plane, leaving a flat lid.
• The drainage checks do not fire, because there is nothing sealed to drain.
• Explode in the CAD toolbar separates the halves so you can inspect the bonding faces.

The cost is a bond, and a bond is a seam that can leak.

Monolithic

One sealed block with the channels as internal voids. No bonding, no seam, nothing to align.

The cost is drainage. Uncured resin inside a sealed channel does not stay liquid — it sets, and at that point the channel is gone. This is the failure that ruins most first chips.

If you choose monolithic, read Draining uncured resin from channels before you print, and expect to add vents.

Glass slide

One open-faced part with a pocket cut for a glass microscope slide, which becomes the lid. The channels are grooves with no roof, so they rinse out like a two-piece chip, and what closes them is flat optical glass rather than a printed surface.

A Glass slide section appears on the panel with the slide’s dimensions:

Parameter	Default	What it is
Slide width	75 mm	Slide footprint along X.
Slide length	25 mm	Slide footprint along Y.
Slide thickness	1 mm	Sets how deep the pocket is cut. Plain slides run 1.0–1.2 mm.
Fit clearance	0.2 mm	Extra pocket size per side, so the glass drops in rather than presses in.
Bond gap	0 mm	Extra pocket depth under the glass, for adhesive.
Offset X / Y	0 mm	Moves the pocket from the middle of the chip.

The last three are under Advanced. A ↻ 90° button beside the width and length fields swaps them — turning the slide in place without retyping both numbers, for when the pocket is oriented across the design rather than along it.

Split height does nothing here. The channels open onto the pocket floor, which is baseThickness − (thickness + bond gap), and the panel shows the figure it works out to as Channel plane, in place of the split height field. Ports must sit outside the pocket, since the glass would otherwise bond over them.

See Capping with a glass slide.

The full comparison, including when monolithic is genuinely the right answer, is on Monolithic vs. two-piece.

Split height

Where the cut plane sits, measured from the bottom of the block. 2 mm by default, which is the mid-plane of the default 4 mm chip.

Rectangular channels are placed so their ceiling is at the cut plane. Raise the split height and you get a thicker channel plate and a thinner lid; lower it and the reverse.

On a monolithic chip nothing is cut, but the split height still sets how deep the channels sit in the block.

Caution

A split height outside the block means no cut happens and the chip prints as a sealed solid, even though the split type says two-piece. That is easy to do by accident — lower the base thickness below the split height, or drag the split height to either end of its slider, and the geometry silently becomes monolithic.

The enclosed-cavity check catches this case specifically, and the warning says why.

What the panel also tells you

Above the parameters, a line of statistics from the last build: triangle count, build time, channel void volume, port count, chamber count, and the drainage vent count when there are any.

Channel void volume is the useful one. It is the internal volume of the chip in mm³ — how much fluid it holds, and how much uncured resin you will need to flush out.

Next

• The 3D preview — driving the viewport.
• Exporting — getting the STL out.